Fish were reared in fifteen glass aquaria for 84 days, three replicates per treatment. Ten fingerlings of Keeled mullet were placed per aquarium with an average weight 1.41 ± 0.3 g fish. Fish were fed twice daily (six days a week) at a rate of 5% of body weight on dry matter basis. The results showed that fish fed on diets (4 and 5) supplemented with 60 and 80 mg kg-1 were significantly (P≤0.05) have higher growth rate (5.7±1.0) than fish fed other diets and different from control diet (1) in its effect on fish weight and growth and feed utilization performances. The different maturity of stages due to increasing Rumalato level, which reach maximum maturity at stage III (Developing Stage) when fish fed on diet 4, supplemented with 60 mg kg-1 Rumalato. It was showed that increasing level of Rumalato, body moisture content and fat content increased. It was concluded that, Rumalato supplemented in diets could improve performance, growth rate and gonad maturity of mullet without adverse effect. Source: El-Halafawy et al. (2012). Res J Agr Environ Manag, 1(1): 012-020